If wireless communication is used to remotely control an electronic device such as a television receiver, the 2.4 GHz band ISM (Industrial, Scientific, and Medical use) band has advantages in that the influence of shield objects becomes smaller compared to infrared protocols, and additionally, the reach distance is extended. Furthermore, since the receiving side returns an acknowledgement and retransmission is conducted even if communication fails, there is an advantage in that operations are reliably transmitted.
In a remote control system according to such wireless communication (hereinafter abbreviated to RF as appropriate), there is a problem of unintentionally controlling devices installed in an adjacent room or adjacent home. For this reason, when newly purchasing and installing a television receiver, a one-to-one association (referred to as pairing) is necessary in order to enable control of the television receiver by a commander (referred to as a remote controller where appropriate). Pairing means exchanging mutual IDs (identification information) between a remote controller and an electronic device to be controlled.
In commercially available wireless LAN devices, pairing may be made by directly inputting an ID. With this method, input operations are troublesome in the case of devices widely used in homes, such as television receivers. If the number of digits in an ID is reduced, the probability that a third party will be able to conduct pairing increases. Since a keypad is necessary to input an ID, there is a problem in that realization is difficult in the case of devices not having a keypad, such as wireless headphones.
In order to simplify operations for pairing, there are configurations that enable pairing by turning the power of a remote controller ON (setting the battery or batteries) within a given amount of time since turning the power of a television device ON. With this method, a third party may conduct pairing with that television receiver by conducting a similar operation. As a result, there occurs risk that personal information for television shopping or the like and secure information such as credit card security codes may be stolen.
As another pairing method, there is also a method wherein a purchased television receiver enters an operational state for conducting pairing (pairing mode) only in the case of first turning the power ON, and pairing mode ends when pairing succeeds. With this method, only a single commander can be paired to a single television receiver. However, there occur concerns that if pairing is conducted by a third party, the original user will become unable to conduct pairing.
Furthermore, as disclosed in Japanese Unexamined Patent Application Publication No. 2007-251637 and Japanese Unexamined Patent Application Publication No. 2008-131532, it is proposed that the electric field strength received by a television receiver be compared to a threshold value, and only a commander whose strength is equal to or greater than the threshold value be taken as a pairing target.